- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- BUGS
- SEE ALSO
- HISTORY

# NAME

BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM assignment operations

# SYNOPSIS

     #include <openssl/bn.h>

     int BN_zero(BIGNUM *a);
     int BN_one(BIGNUM *a);

     const BIGNUM *BN_value_one(void);

     int BN_set_word(BIGNUM *a, BN_ULONG w);
     BN_ULONG BN_get_word(BIGNUM *a);

# DESCRIPTION

BN_ULONG is a macro that will be an unsigned integral type optimied for the most efficient implementation on the local platform.

BN_zero(), `BN_one()` and `BN_set_word()` set a to the values 0, 1 and w respectively. `BN_zero()` and `BN_one()` are macros.

`BN_value_one()` returns a BIGNUM constant of value 1. This constant is useful for use in comparisons and assignment.

`BN_get_word()` returns a, if it can be represented as a BN_ULONG.

# RETURN VALUES

`BN_get_word()` returns the value a, or all-bits-set if a cannot be represented as a BN_ULONG.

BN_zero(), `BN_one()` and `BN_set_word()` return 1 on success, 0 otherwise. `BN_value_one()` returns the constant.

# BUGS

If a BIGNUM is equal to the value of all-bits-set, it will collide with the error condition returned by `BN_get_word()` which uses that as an error value.

BN_ULONG should probably be a typedef.

# SEE ALSO

bn, BN_bn2bin

# HISTORY

BN_zero(), `BN_one()` and `BN_set_word()` are available in all versions of SSLeay and OpenSSL. `BN_value_one()` and `BN_get_word()` were added in SSLeay 0.8.

`BN_value_one()` was changed to return a true const BIGNUM * in OpenSSL 0.9.7.